Plasma processing method and apparatus

ABSTRACT

A plasma processing method includes exhausting interior of a vacuum chamber while supplying gas into the vacuum chamber, and while controlling the interior of the vacuum chamber to a pressure, applying a high-frequency power of 100 kHz to 100 MHz to a coil provided in a vicinity of a dielectric window provided so as to face a substrate placed on a substrate electrode in the vacuum chamber, and thus generating plasma in the vacuum chamber to process the substrate or a film on the substrate by the generated plasma while particles which tend to move straight from a surface of the substrate or from a surface of the film on the substrate toward a wall surface of the dielectric window inside the vacuum chamber are kept interrupted by a metal plate.

BACKGROUND OF THE PRESENT INVENTION

[0001] The present invention relates to a plasma processing method andapparatus, such as an etching method and apparatus, to be used formanufacture of semiconductor or other electron equipments andmicromachines.

[0002] For manufacture of semiconductor or other electron equipments andmicromachines, demands for etching techniques related to refractorymetal films have been increasing year after year.

[0003] For example, in the field of semiconductor memories (storagedevices), although countermeasures for increases in the capacitance ofmemory capacitors have hitherto been given by changing the memorycapacitor structure, it has become difficult to secure demandedcapacitances only by the structure change with progress ofminiaturizing. Due to this, ceramic base oxides having high dielectricconstants such as barium/strontium titanate, lead zirconium titanate,and bismuth/strontium tantalate have come to be used as materials forcapacitor capacitance. Since elimination of oxygen from these ceramicbase oxides would cause their characteristics to largely deteriorate,such materials exhibiting low reaction with oxygen as ruthenium,platinum, iridium, and rhodium are used as materials for capacitorelectrodes. Forming microfine patterns by using these materials requiresetching techniques for those materials.

[0004] Moreover, not only for Si-based semiconductors but also forcompound semiconductors, there has arisen a need for an etching processthat contact holes are formed in an insulator film with a refractorymetal film used as an undercoat film. In this case, although theinsulator film is targeted for the etching, the refractory metal, whichis the undercoat film, also would be etched to some extent inoveretching.

[0005] An etching using an inductively coupled plasma source as anexample of the prior-art etching method is explained below withreference to FIG. 7. Referring to FIG. 7, while a vacuum chamber 1 ismaintained at a specified internal pressure by exhausting the vacuumchamber 1 with a turbo-molecular pump 3 serving as an exhausted andsimultaneously leading a specified gas from a gas supply equipment 2into the vacuum chamber 1, a high-frequency power of 13.56 MHz issupplied to a coil 6 provided on a dielectric plate 20 by means of acoil-use high-frequency power supply 4, by which plasma is generated inthe vacuum chamber 1, allowing the etching on a substrate 8 placed on asubstrate electrode 7 to be achieved. Further, a substrate-electrode usehigh-frequency power supply 9 for supplying a high-frequency power of400 kHz to the substrate electrode 7 is provided, allowing ion energyreaching the substrate 8 to be controlled.

[0006] The turbo-molecular pump 3 and an exhaust port 10 are disposedjust under the substrate electrode 7, and a pressure-controlling valve11 for controlling the vacuum chamber 1 to the specified pressure is anup-down valve located just under the substrate electrode 7 and just overthe turbo-molecular pump 3.

[0007] With an etching apparatus having such a constitution, an iridiumfilm can be etched under the conditions of an Ar/Cl₂ of 260/20 sccm, apressure of 0.3 Pa, and an ICP (coil power)/BIAS (substrate-electrodepower) of 1500/400 W.

[0008] Further, a silicon oxide film on a gold film can be etched underthe conditions of an Ar/CHF₃ of 270/30 sccm, a pressure of 2.5 Pa, andan ICP/BIAS of 1500/600 W.

[0009] However, in the etching of iridium described in the prior artexample, which consists mainly of physical etching, an electricallyconductive iridium thin film would deposit on the surface of thedielectric plate 20, so that a high-frequency electromagnetic fieldgenerated in the vacuum chamber 1 as a result of supplyinghigh-frequency power to the coil 6 would be gradually weakened and adecline of the etching rate would occur as an issue as shown in FIG. 8.

[0010] Also, in the etching of a silicon oxide film described in theprior art example, in which gold forming an undercoat film would beetched to some extent in overetching, where the etching of gold alsoconsists mainly of physical etching, an electrically conductive goldthin film would be deposited on the surface of the dielectric plate 20,so that a high-frequency electromagnetic field generated in the vacuumchamber 1 as a result of supplying high-frequency power to the coil 6would be gradually weakened and a decline of the etching rate wouldoccur as an issue as shown in FIG. 9.

SUMMARY OF THE PRESENT INVENTION

[0011] The present invention having been accomplished in view of theseand other prior-art issues, an object of the present invention is toprovide a plasma processing method and apparatus capable of achievinguniform plasma processing and ensuring a stable etching rate.

[0012] In accomplishing these and other aspects, according to a firstaspect of the present invention, there is provided a plasma processingmethod comprising:

[0013] exhausting interior of a vacuum chamber while supplying gas intothe vacuum chamber; and

[0014] while controlling the interior of the vacuum chamber to apressure, applying a high-frequency power of 100 kHz to 100 MHz to acoil provided in a vicinity of a dielectric window provided so as toface a substrate placed on a substrate electrode in the vacuum chamber,and thus generating plasma in the vacuum chamber to process thesubstrate or a film on the substrate by the generated plasma whileparticles which tend to move straight from a surface of the substrate orfrom a surface of the film on the substrate toward a wall surface of thedielectric window inside the vacuum chamber are kept interrupted by ametal plate.

[0015] According to a second aspect of the present invention, there isprovided a plasma processing method according to the first aspect,wherein when the plasma is generated inside the vacuum chamber, thehigh-frequency power of 100 kHz to 100 MHz is applied to the coilprovided inside a dielectric cylinder serving as the dielectric windowand outside a vacuum chamber.

[0016] According to a third aspect of the present invention, there isprovided a plasma processing method according to the first or secondaspect, wherein the plasma processing is a process of etching thesubstrate or the film on the substrate.

[0017] According to a fourth aspect of the present invention, there isprovided a plasma processing method according to the first or secondaspect, wherein the plasma processing is a process of etching arefractory metal film on the substrate.

[0018] According to a fifth aspect of the present invention, there isprovided a plasma processing method according to the first or secondaspect, wherein the plasma processing is a process of etching a thinfilm formed on a refractory metal film on the substrate.

[0019] According to a sixth aspect of the present invention, there isprovided a plasma processing method according to the fourth or fifthaspect, wherein the refractory metal film is a film containing at leastone element of iridium, rhodium, ruthenium, platinum, gold, copper,rhenium, bismuth, strontium, barium, zirconium, lead, and niobium.

[0020] According to a seventh aspect of the present invention, there isprovided a plasma processing method according to the second aspect,wherein the high-frequency power of 100 kHz to 100 MHz is applied to thecoil provided outside the vacuum chamber on a dielectric cylinderserving as the dielectric window in a state that a first metal plateprovided at a bottom portion of the dielectric cylinder inside thevacuum chamber is connected to a second metal plate provided at an upperportion of the dielectric cylinder on its one side opposite to thebottom portion inside the vacuum chamber by means of a metal rod or boltextending through a penetration hole provided along an axis of thedielectric cylinder while the dielectric cylinder is fixed by beingsandwiched between the first metal plate and the second metal plate.

[0021] According to an eighth aspect of the present invention, there isprovided a plasma processing method according to the second aspect,wherein the high-frequency power of 100 kHz to 100 MHz is applied to thecoil provided outside the vacuum chamber on a dielectric cylinderserving as the dielectric window in a state that a first metal plateprovided at a bottom portion of the dielectric cylinder inside thevacuum chamber is connected to a second metal plate provided at an upperportion of the dielectric cylinder on its one side opposite to thebottom portion inside the vacuum chamber by means of a metal rod or boltdisposed outside the vacuum chamber on the dielectric cylinder while thedielectric cylinder is fixed by being sandwiched between the first metalplate and the second metal plate.

[0022] According to a ninth aspect of the present invention, there isprovided a plasma processing method according to the seventh or eighthaspect, wherein the metal rod or bolt, the first metal plate, and thesecond metal plate are at a ground potential.

[0023] According to a 10th aspect of the present invention, there isprovided a plasma processing method according to the seventh or eighthaspect, wherein the processing is carried out in a state that a linesegment interconnecting an arbitrary point on a vacuum-side wall surfaceof the dielectric cylinder and an arbitrary point on a surface of thesubstrate is interrupted by the first metal plate provided at the bottomof the dielectric cylinder.

[0024] According to an 11th aspect of the present invention, there isprovided a plasma processing method according to the seventh or eighthaspect, wherein a diameter of the first metal plate is 1 to 1.5 timeslarger than a diameter of the substrate electrode and a diameter of thesecond metal plate is 1.6 to 3 times larger than a diameter of thesubstrate electrode.

[0025] According to a 12th aspect of the present invention, there isprovided a plasma processing method according to the seventh or eighthaspect, wherein a distance between the first metal plate and thesubstrate electrode is 40 mm to 150 mm.

[0026] According to a 13th aspect of the present invention, there isprovided a plasma processing method according to the first or secondaspect, wherein the vacuum chamber has a pressure not more than 10 Pa.

[0027] According to a 14th aspect of the present invention, there isprovided a plasma processing method according to the first or secondaspect, wherein the vacuum chamber has a pressure not more than 3 Pa.

[0028] According to a 15th aspect of the present invention, there isprovided a plasma processing apparatus comprising:

[0029] a vacuum chamber;

[0030] a gas supply equipment for supplying gas into the vacuum chamber;

[0031] an exhaust equipment for exhausting the vacuum chamber;

[0032] a pressure-controlling valve for controlling the vacuum chamberto an internal pressure;

[0033] a substrate electrode for placing thereon a substrate in thevacuum chamber;

[0034] a dielectric window provided so as to face the substrateelectrode;

[0035] a coil provided in a vicinity of the dielectric window; and

[0036] a high-frequency power supply equipment capable of supplying ahigh-frequency power of 100 kHz to 100 MHz to the coil,

[0037] wherein a line segment interconnecting an arbitrary point on avacuum-side wall surface of the dielectric window and an arbitrary pointon a surface of the substrate is interrupted by a metal plate.

[0038] According to a 16th aspect of the present invention, there isprovided a plasma processing apparatus comprising:

[0039] a vacuum chamber;

[0040] a gas supply equipment for supplying gas into the vacuum chamber;

[0041] an exhaust equipment for exhausting the vacuum chamber; apressure-controlling valve for controlling the vacuum chamber to aninternal pressure;

[0042] a substrate electrode for placing thereon a substrate in thevacuum chamber;

[0043] a dielectric cylinder provided so as to face the substrateelectrode;

[0044] a coil provided inside the dielectric cylinder and outside thevacuum chamber; and

[0045] a high-frequency power supply equipment capable of supplying ahigh-frequency power of 100 kHz to 100 MHz to the coil.

[0046] According to a 17th aspect of the present invention, there isprovided a plasma processing apparatus according to the 16th aspect,further comprising:

[0047] a first metal plate provided at a one-side bottom of thedielectric cylinder facing the substrate electrode; and

[0048] a second metal plate provided at the other side bottom of thedielectric cylinder not facing the substrate electrode,

[0049] wherein the first metal plate is connected to the second metalplate by means of a metal rod or a bolt extending through a penetrationhole provided along a cylinder axis of the dielectric cylinder while thedielectric cylinder is fixed by being sandwiched between the first metalplate and the second metal plate.

[0050] According to an 18th aspect of the present invention, there isprovided a plasma processing apparatus according to the 16th aspect,further comprising:

[0051] a first metal plate provided at a one-side bottom of thedielectric cylinder facing the substrate electrode; and

[0052] a second metal plate provided at the other side bottom of thedielectric cylinder not facing the substrate electrode,

[0053] wherein the first metal plate is connected to the second metalplate by means of a metal rod or a bolt provided through a space insidethe dielectric cylinder while the dielectric cylinder is fixed by beingsandwiched between the first metal plate and the second metal plate.

[0054] According to a 19th aspect of the present invention, there isprovided a plasma processing apparatus according to the 17th or 18thaspect, wherein the metal rod or bolt, the first metal plate, and thesecond metal plate are at a ground potential.

[0055] According to a 20th aspect of the present invention, there isprovided a plasma processing apparatus according to the 17th or 18thaspect, wherein a line segment interconnecting an arbitrary point on avacuum-side wall surface of the dielectric cylinder and an arbitrarypoint on a surface of the substrate is interrupted by the first metalplate provided at the bottom of the dielectric cylinder.

[0056] According to a 21st aspect of the present invention, there isprovided a plasma processing apparatus according to the 17th or 18thaspect, wherein a diameter of the first metal plate is 1 to 1.5 timeslarger than a diameter of the substrate electrode and a diameter of thesecond metal plate is 1.6 to 3 times larger than a diameter of thesubstrate electrode.

[0057] According to a 22nd aspect of the present invention, there isprovided a plasma processing apparatus according to the 17th or 18thaspect, wherein a distance between the first metal plate and thesubstrate electrode is 40 mm to 150 mm.

[0058] According to a 23rd aspect of the present invention, there isprovided an etching method comprising:

[0059] controlling interior of a vacuum chamber to a pressure byexhausting the vacuum chamber while supplying gas into the vacuumchamber; and

[0060] applying a high-frequency power of 100 kHz to 100 MHz to a coilprovided inside a dielectric cylinder and outside the vacuum chamberprovided so as to face a substrate placed on a substrate electrode inthe vacuum chamber, thus generating plasma in the vacuum chamber so asto etch a refractory metal film on the substrate.

[0061] According to a 24th aspect of the present invention, there isprovided an etching method comprising:

[0062] controlling interior of a vacuum chamber to a pressure byexhausting the vacuum chamber while supplying gas into the vacuumchamber; and

[0063] applying a high-frequency power of 100 kHz to 100 MHz to a coilprovided inside a dielectric cylinder and outside the vacuum chamberprovided so as to face a substrate placed on a substrate electrode inthe vacuum chamber thus, generating plasma in the vacuum chamber so asto etch a thin film formed on a refractory metal film on the substrate.

[0064] According to a 25th aspect of the present invention, there isprovided an etching method according to the 23rd or 24th aspect, whereinthe refractory metal film is a film containing at least one element ofiridium, rhodium, ruthenium, platinum, gold, copper, rhenium, bismuth,strontium, barium, zirconium, lead, and niobium.

[0065] According to a 26th aspect of the present invention, there isprovided an etching method according to the 23rd or 24th aspect, whereinthe etching is carried out in a state that a first metal plate providedat a one-side bottom of the dielectric cylinder facing the substrateelectrode is connected to a second metal plate provided at the otherside bottom of the dielectric cylinder not facing the substrateelectrode, by means of a metal rod or a bolt extending through apenetration hole provided along a cylinder axis of the dielectriccylinder while the dielectric cylinder is fixed by being sandwichedbetween the first metal plate and the second metal plate.

[0066] According to a 27th aspect of the present invention, there isprovided an etching method according to the 23rd or 24th aspect, whereinthe etching is carried out in a state that a first metal plate providedat a one-side bottom of the dielectric cylinder facing the substrateelectrode is connected to a second metal plate provided at the otherside bottom of the dielectric cylinder not facing the substrateelectrode, by means of a metal rod or a bolt provided in a space insidethe dielectric cylinder while the dielectric cylinder is fixed by beingsandwiched between the first metal plate and the second metal plate.

[0067] According to a 28th aspect of the present invention, there isprovided an etching method according to the 26th or 27th aspect, whereinthe metal rod or bolt, the first metal plate, and the second metal plateare at a ground potential.

BRIEF DESCRIPTION OF THE DRAWINGS

[0068] These and other aspects and features of the present inventionwill become clear from the following description taken in conjunctionwith the preferred embodiments thereof with reference to theaccompanying drawings, in which:

[0069]FIG. 1 is a sectional view showing the constitution of an etchingapparatus used in a first embodiment of the present invention;

[0070]FIG. 2 is an enlarged and partially sectional view showing theconstitution of the etching apparatus used in the first embodiment ofthe present invention;

[0071]FIG. 3 is a graph showing variations in the etching rate in thefirst embodiment of the present invention;

[0072]FIG. 4 is a sectional view showing the constitution of an etchingapparatus used in a second embodiment of the present invention;

[0073]FIG. 5 is an enlarged and partially sectional view showing theconstitution of the etching apparatus used in the second embodiment ofthe present invention;

[0074]FIG. 6 is a graph showing variations in the etching rate in thesecond embodiment of the present invention;

[0075]FIG. 7 is a sectional view showing the constitution of an etchingapparatus used in the prior art example;

[0076]FIG. 8 is a graph showing variations in the etching rate in theprior art example;

[0077]FIG. 9 is a graph showing variations in the etching rate inanother prior art example;

[0078]FIG. 10 is a plan view of the etching apparatus of FIG. 1; and

[0079]FIG. 11 is an enlarged and partially sectional view showing theconstitution of an etching apparatus used in a third embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0080] Before the description of the present invention proceeds, it isto be noted that like parts are designated by like reference numeralsthroughout the accompanying drawings.

[0081] Hereinbelow, a first embodiment of the present invention isdescribed with reference to FIGS. 1 to 3 and 10.

[0082]FIG. 1 shows a sectional view of an etching apparatus as anexample of a plasma processing apparatus used in a first embodiment ofthe present invention. Referring to FIG. 1, while a vacuum chamber 1 ismaintained at a specified internal pressure by exhausting the vacuumchamber 1 with a turbo-molecular pump 3 serving as an exhauster andsimultaneously leading a specified gas from nozzles 2A of a gas supplyequipment 2 into the vacuum chamber 1, a high-frequency power of 13.56MHz is supplied by means of a coil-use high-frequency power supplyequipment 4 to a coil 6 provided inside a dielectric cylinder 5 whichserves as one example of a dielectric window and is formed of glass orceramics, such as quartz glass, alumina, aluminum nitride or siliconnitride (SiN₄), by which plasma is generated in the vacuum chamber 1,thus allowing the etching on a substrate 8 or a thin film thereon placedon a substrate electrode 7 to be achieved. Further, asubstrate-electrode use high-frequency power supply equipment 9 forsupplying a high-frequency power of 400 kHz to the substrate electrode 7is provided, allowing ion energy reaching the substrate 8 to becontrolled. Examples of the thin films on the substrate 8 are a siliconoxide film, a silicon nitride film, etc.

[0083] The turbo-molecular pump 3 and an exhaust port 10 are disposedjust under the substrate electrode 7, and a pressure-controlling valve11 for controlling the vacuum chamber 1 to the specified pressure is anup-down valve located just under the substrate electrode 7 and just overthe turbo-molecular pump 3. Thus, the pressure-controlling valve 11moves up and down to control the pressure the vacuum chamber 1 to set tothe specified pressure. Thus, the pressure-controlling valve 11 moves upand down to control the pressure the vacuum chamber 1 to set to thespecified pressure.

[0084] A first metal plate 12 made of aluminum and having analumite-coated surface as an example is provided at a one-side bottom ofthe dielectric cylinder 5 facing the substrate electrode 7, and a secondmetal plate 13 made of aluminum and having an alumite-coated surface asan example is provided at the other side bottom of the dielectriccylinder 5 not facing the substrate electrode 7. The first metal plate12 is connected to the second metal plate 13 by means of plural bolts 15made of stainless as an example and extending through penetration holes14 provided in the dielectric cylinder 5 along the cylinder axis of thedielectric cylinder 5, and the dielectric cylinder 5 is fixed by beingsandwiched between the first metal plate 12 and the second metal plate13. That is, as shown in FIG. 2, the dielectric cylinder 5 is located onthe outer edge of the first metal plate 12, and the outer edge of thefirst metal plate 12 and the inner edge of the dielectric cylinder 5 arelocated on the inner edge of the second metal plate 13 while the bolts15 are connected between the first metal plate 13 and the second metalplate 12 through the dielectric cylinder 5. The bolts 15, the firstmetal plate 12, and the second metal plate 13 are at the groundpotential.

[0085] Also, as shown in FIG. 2, a line segment interconnecting anarbitrary point A on the vacuum-side wall surface of the dielectriccylinder 5 and an arbitrary point B on the substrate surface isinterrupted by the first metal plate 12 provided at the bottom of thedielectric cylinder 5. That is, when plasma processing is carried out,particles which tend to move straight from a surface of the substrate 8or from a surface of the film on the substrate 8 toward a wall surfaceof the dielectric cylinder 5 inside the vacuum chamber 1 through theplasma processing can be kept interrupted by the first metal plate 12,thus preventing deposition of a thin film on the dielectric cylinder 5.

[0086] With the etching apparatus having such a constitution, an iridiumfilm was etched under the conditions of an Ar/Cl₂ of 260/20 sccm, apressure of 0.3 Pa, and an ICP (coil power)/BIAS (substrate-electrodepower) of 1500/400 W. A transition of etching rate is shown in FIG. 3.As apparent from FIG. 3, such declines of etching rate as seen in theprior art example have been eliminated.

[0087] The reason why a stable etching rate has been ensured as shownabove can be considered that the iridium thin film is no longerdeposited on the surface of the dielectric cylinder 5 so that thehigh-frequency electromagnetic field generated in the vacuum chamber 1as a result of supplying the high-frequency power to the coil 6 hasbecome stable in strength.

[0088] Next, a second embodiment of the present invention is describedwith reference to FIGS. 4 to 6.

[0089]FIG. 4 shows a sectional view of an etching apparatus used in thesecond embodiment of the present invention. Referring to FIG. 4, while avacuum chamber 1 is maintained at a specified internal pressure byexhausting the vacuum chamber 1 with a turbo-molecular pump 3 serving asan exhauster and simultaneously leading a specified gas from a gassupply equipment 2 into the vacuum chamber 1, a high-frequency power of13.56 MHz is supplied by means of a coil-use high-frequency power supply4 to a coil 6 provided inside a dielectric cylinder 5 serving as oneexample of a dielectric window, by which plasma is generated in thevacuum chamber 1, thus allowing the etching on a substrate 8 or a thinfilm thereon placed on a substrate electrode 7 to be achieved. Further,a substrate-electrode use high-frequency power supply 9 for supplying ahigh-frequency power of 400 kHz to the substrate electrode 7 isprovided, allowing ion energy reaching the substrate 8 to be controlled.Examples of the thin films on the substrate 8 are a silicon oxide film,a silicon nitride film, etc.

[0090] The turbo-molecular pump 3 and an exhaust port 10 are disposedjust under the substrate electrode 7, and a pressure-controlling valve11 for controlling the vacuum chamber 1 to the specified pressure is anup-down valve located just under the substrate electrode 7 and just overthe turbo-molecular pump 3. Thus, the pressure-controlling valve 11moves up and down to control the pressure the vacuum chamber 1 to set tothe specified pressure. Thus, the pressure-controlling valve 11 moves upand down to control the pressure the vacuum chamber 1 to set to thespecified pressure.

[0091] A first metal plate 12 is provided at a one-side bottom of thedielectric cylinder 5 facing the substrate electrode 7, and a secondmetal plate 13 is provided at the other side bottom of the dielectriccylinder 5 not facing the substrate electrode 7. The first metal plate12 is connected to the second metal plate 13 by means of plural bolts 15provided through a space inside the dielectric cylinder 5 and outsidethe vacuum chamber 1, and the dielectric cylinder 5 is fixed by beingsandwiched between the first metal plate 12 and the second metal plate13. That is, as shown in FIG. 5, the dielectric cylinder 5 is located onthe outer edge of the first metal plate 12, and the outer edge of thefirst metal plate 12 and the inner edge of the dielectric cylinder 5 arelocated outside of the inner edge of the second metal plate 13 while thebolts 15 are connected between the first metal plate 13 and the secondmetal plate 12 except for the dielectric cylinder 5. The bolts 15, thefirst metal plate 12, and the second metal plate 13 are at the groundpotential.

[0092] Also, as shown in FIG. 5, a line segment interconnecting anarbitrary point A on the vacuum-side wall surface of the dielectriccylinder 5 and an arbitrary point B on the substrate surface isinterrupted by the first metal plate 12 provided at the bottom of thedielectric cylinder 5. That is, when plasma processing is carried out,particles which tend to move straight from a surface of the substrate 8or from a surface of the film on the substrate 8 toward a wall surfaceof the dielectric cylinder 5 inside the vacuum chamber 1 through theplasma processing can be kept interrupted by the first metal plate 12,thus preventing deposition of a thin film on the dielectric cylinder 5.

[0093] With the etching apparatus having such a constitution, a siliconoxide film on a gold film was etched under the conditions of an Ar/CHF₃of 270/30 sccm, a pressure of 2.5 Pa, and an ICP/BIAS of 1500/600 W. Atransition of etching rate is shown in FIG. 6. As apparent from FIG. 6,such declines of etching rate as seen in the prior art example have beeneliminated.

[0094] The reason why a stable etching rate has been ensured as shownabove can be considered that the gold thin film is no longer depositedon the surface of the dielectric cylinder 5 so that the high-frequencyelectromagnetic field generated in the vacuum chamber 1 as a result ofsupplying the high-frequency power to the coil 6 has become stable instrength.

[0095] The above-described embodiments of the present invention showonly part of many variations in terms of the configuration of the vacuumchamber, the configuration and placement of the coil and the dielectriccylinder or the like by way of example out of the scope of applicationof the present invention. It is needless to say that wide variations inaddition to the examples shown hereinabove are possible in theapplication of the present invention.

[0096] Although the above embodiments of the present invention have beendescribed about the etching of an iridium film and the etching of asilicon oxide film formed on a gold film, the present invention isuseful for the etching of a refractory metal film and the etching of athin film formed on a refractory metal film. Among such aspects ofetching, this etching method is useful particularly for cases where therefractory metal film is a film containing at least one element ofiridium, rhodium, ruthenium, platinum, gold, copper, rhenium, bismuth,strontium, barium, zirconium, lead, and niobium.

[0097] The above embodiments of the present invention have beendescribed on a case where the first metal plate is provided at aone-side bottom of the dielectric cylinder facing the substrateelectrode while the second metal plate is provided at the other sidebottom of the dielectric cylinder not facing the substrate electrode,where the first metal plate is connected to the second metal plate bymeans of bolts extending a through penetration holes provided in thedielectric cylinder along the cylinder axis of the dielectric cylinderwhile the dielectric cylinder is fixed by being sandwiched between thefirst and second metal plates, in which state the etching is performed,as well as a case where the first metal plate is provided at a one-sidebottom of the dielectric cylinder facing the substrate electrode whilethe second metal plate is provided at the other side bottom of thedielectric cylinder not facing the substrate electrode, where the firstmetal plate is connected to the second metal plate by means of boltsprovided through a space inside the dielectric cylinder while thedielectric cylinder is fixed by being sandwiched between the first andsecond metal plates, in which state the etching is performed. However,various constitutions other than these are possible, of course. Forexample, the first and second metal plates may be connected to eachother by using a metal rod instead of the bolt.

[0098] Also, the above embodiments of the present invention have beendescribed on a case where the bolt, the first metal plate, and thesecond metal plate are at the ground potential. Since such aconstitution allows the capacitive coupling between the coil and theplasma to be suppressed, self-biased potential is unlikely to occur tothe surface of the dielectric cylinder, offering an advantage that thesurface of the dielectric cylinder is less etched. In addition, forprevention of inductive heating at the bolt or the metal rod, it isdesirable that the bolt or the metal rod be coated or plated with alow-resistivity film.

[0099] Also, the above embodiments of the present invention have beendescribed on a case where a line segment interconnecting an arbitrarypoint on the vacuum-side wall surface of the dielectric cylinder and anarbitrary point on the substrate surface is interrupted by the firstmetal plate provided at the bottom of the dielectric cylinder, in whichstate the etching is performed. However, this interruption does notnecessarily need to be perfect, and the design may be given some degreeof freedom within such a scope as declines of etching rate do not occur.

[0100] Also, the above embodiments of the present invention have beendescribed on a case where the turbo-molecular pump for exhausting thevacuum chamber is disposed just under the substrate electrode while thepressure-controlling valve for controlling the vacuum chamber to aspecified pressure is an up-down valve located just under the substrateelectrode and just over the turbo-molecular pump. Moreover, the presentinvention is useful also for cases where the turbo-molecular pump 3 isdisposed other than just under the substrate electrode 7 while thepressure-controlling valve 11 is disposed other than just under thesubstrate electrode 7 and other than an up-down valve. However, theembodiments of the present invention, in which gas exhaust is doneisotropically, offer an advantage that the etching can be achieveduniformly.

[0101] Further, although the description has been made on cases wherethe internal pressure of the vacuum chamber is 0.3 Pa and 2.5 Pa, themethod of the present invention is useful for cases where the internalpressure of the vacuum chamber is not more than 10 Pa since the lowerthe internal pressure of the vacuum chamber is, the larger part thephysical etching forms. The method of the present invention is usefulparticularly for cases where the internal pressure of the vacuum chamberis not more than 1 Pa.

[0102] Further, although the description has been made on a case wherethe frequency of the high-frequency power applied to the coil is 13.56MHz, the method of the present invention allows high-frequency powers of100 kHz to 100 MHz to be used for the etching at low pressure, thusbeing useful for all of those regions.

[0103] Further, although the description has been made on a case wherethe frequency of the high-frequency power applied to the substrateelectrode is 400 kHz, the method of the present invention, needless tosay, allows other frequencies, for example, high-frequency powers of 100kHz to 100 MHz to be used for the control of ion energy reaching thesubstrate.

[0104] The dielectric cylinder 5 may be structured longitudinallylonger. In this case, since the region for high dissociation of plasmaoccupies an increased volume, there can be obtained a characteristicthat active particles of further dissociated composition can be made toact on the substrate 8.

[0105] In an etching apparatus of a third embodiment of the presentinvention, a dielectric ring 22 instead of the dielectric cylinder 5which can be served as a dielectric window is fitted into a hole of asecond metal plate 13B so as to locate the dielectric ring 22 as aninner edge of the second metal plate 13B. The inner edge of thedielectric ring 22 is brought into contact with the outer edge of afirst metal plate 21 from the lower side of the dielectric ring 22 whilethe inner edge of the dielectric ring 22 and the outer edge of the firstmetal plate 21 are directly connected with bolts 15. The coil 6 isprovided outside the dielectric ring 22.

[0106] In such a construction, as shown in FIG. 11, a line segmentinterconnecting an arbitrary point A on the vacuum-side wall surface ofthe dielectric ring 22 and an arbitrary point B on the substrate surfaceis interrupted by the first metal plate 21 provided on the lower side ofthe dielectric ring 22. That is, when plasma processing is carried out,particles which tend to move straight from a surface of the substrate 8or from a surface of the film on the substrate 8 toward a wall surfaceof the dielectric ring 22 inside the vacuum chamber 1 through the plasmaprocessing can be kept interrupted by the first metal plate 21, thuspreventing deposition of a thin film on the dielectric ring 22. Thus,the same effects as the previous embodiments can be obtained in thisthird embodiment.

[0107] Preferably, the diameter 2R₁ of the first metal plate 12 is 1 to1.5 times larger than the diameter 2R₃ of the substrate electrode 7 andthe diameter 2R₂ of the second metal plate 13 is 1.6 to 3 times largerthan the diameter 2R₃ of the substrate electrode 7. Within such acondition range, it becomes possible to form doughnut-shapedhigh-density plasma in the region outside the dielectric cylinder 5 ordielectric plate 21, and to realize uniform plasma density in thevicinity of the substrate 8 through diffusion. If the diameter 2R₁ ofthe first metal plate 12 is smaller than the diameter 2R₃ of thesubstrate electrode 7, a resultant plasma distribution would be oneconvex in the vicinity of the substrate 8. Conversely, if the diameter2R₁ of the first metal plate 12 is larger than 1.5 times the diameter2R₃ of the substrate electrode 7, a resultant plasma distribution wouldbe one concave in the vicinity of the substrate 8. Further, if thediameter 2R₂ of the second metal plate 13 is smaller than 1.6 times thediameter 2R₃ of the substrate electrode 7, enough plasma density couldnot be obtained in peripheries of the substrate 8. Conversely, if thediameter 2R₂ of the second metal plate 13 is larger than 3 times thediameter 2R₃ of the substrate electrode 7, excessive plasma densitywould result in peripheries of the substrate 8.

[0108] Preferably, a distance H₁ between the first metal plate 12 andthe substrate electrode 7 is 40 mm to 150 mm. Within such a conditionrange, it becomes possible to form doughnut-shaped high-density plasmain the region outside the dielectric cylinder 5 or dielectric plate 21,and to realize uniform, high-density plasma in the vicinity of thesubstrate 8 through diffusion. If the distance H₁ between the firstmetal plate 12 and the substrate electrode 7 is smaller than 40 mm,enough diffusion would not be done, resulting a plasma distributionconcave in the vicinity of the substrate 8. Conversely, if the distanceH₁ between the first metal plate 12 and the substrate electrode 7 islarger than 150 mm, excessive diffusion of plasma would occur, resultingin a plasma distribution convex in the vicinity of the substrate 8.

[0109] Preferably, the distance of the metal rod or the bolt is 10 mm to50 mm. If the distance between the adjacent metal rods or the adjacentbolts is smaller than 10 mm, the high-frequency electromagnetic fieldradiated into the vacuum chamber by the coil would decline in strength,leading to a defect that enough plasma density could not be obtained.Also, if the distance between the adjacent metal rods or the adjacentbolts is larger than 50 mm, the metal rods or the bolts would decline inthe function as a faradic shield so that capacitive coupling between thecoil and the plasma would be increased. This is unfavorable in that aself-biased potential would occur to the surface of the dielectriccylinder or plate, causing the surface of the dielectric cylinder orplate to be etched.

[0110] When the dielectric cylinder or plate is considered that thetransmission plane of the high-frequency electromagnetic field is partlyinterrupted by the metal rod or the bolt, in the transmission plate, theratio of an area of part that is not interrupted by the metal rod or thebolt to the area of the whole dielectric cylinder or plate can bedefined as an aperture. The aperture is preferably not less than 50%. Ifthe aperture is smaller than 50%, the high-frequency electromagneticfield radiated into the vacuum chamber by the coil would decline instrength, leading to a defect that enough plasma density could not beobtained.

[0111] The above embodiments of the present invention have beendescribed about the etching of an iridium film as well as the etching ofa silicon oxide film formed on a gold film. However, the presentinvention is applicable to general plasma processing for processing asubstrate or a film on a substrate. Needless to say, etching can beapplied to plasma CVD and the like. Moreover, the present invention isuseful particularly for the etching of a refractory metal film and theetching of a thin film formed on a refractory metal film. Among suchaspects of etching, the method of the present invention is a plasmaprocessing method useful particularly for cases where the refractorymetal film is a film containing at least one element of iridium,rhodium, ruthenium, platinum, gold, copper, rhenium, bismuth, strontium,barium, zirconium, lead, and niobium.

[0112] As apparent from the above description, according to the etchingmethod of the present invention, while the vacuum chamber is controlledto a specified internal pressure by exhausting the vacuum chamber andsimultaneously supplying gas into the vacuum chamber, a high-frequencypower of 100 kHz to 100 MHz is applied to a coil provided inside adielectric window such as a dielectric cylinder or plate provided so asto face a substrate placed on a substrate electrode in the vacuumchamber, by which plasma is generated in the vacuum chamber, therebyprocessing such as etching a substrate or a thin film such as arefractory metal film on the substrate by the generated plasma whileparticles which tend to move straight from a surface of the substrate orfrom a surface of the film on the substrate toward a wall surface of thedielectric window inside the vacuum chamber are kept interrupted by ametal plate. Thus, a processing such as an etching method that allows astable processing such as etching rate to be ensured can be realized.

[0113] Also, according to the etching method of the present invention,while the vacuum chamber is controlled to a specified internal pressureby exhausting the vacuum chamber and simultaneously supplying gas intothe vacuum chamber, a high-frequency power of 100 kHz to 100 MHz isapplied to a coil provided inside a dielectric window such as adielectric cylinder or plate provided so as to face a substrate placedon a substrate electrode in the vacuum chamber, by which plasma isgenerated in the vacuum chamber, thereby processing such as etching athin film formed on a refractory metal film on the substrate by thegenerated plasma while particles which tend to move straight from asurface of the substrate or from a surface of the film on the substratetoward a wall surface of the dielectric window inside the vacuum chamberare kept interrupted by a metal plate. Thus, processing such as anetching method that allows a stable processing such as etching rate tobe ensured can be realized.

[0114] Also, according to the etching apparatus of the presentinvention, the apparatus comprises a vacuum chamber as well as a gassupply equipment for supplying gas into the vacuum chamber, anexhausting equipment for exhausting the vacuum chamber as well as apressure-controlling valve for controlling the vacuum chamber to aspecified internal pressure, a substrate electrode for placing thereon asubstrate in the vacuum chamber, a dielectric window such as adielectric cylinder or plate provided so as to face the substrateelectrode, and a coil provided inside the dielectric window such as adielectric cylinder or plate as well as a high-frequency power supplycapable of supplying a high-frequency power of 100 kHz to 100 MHz to thecoil. Thus, processing such as an etching apparatus that allows a stableprocessing such as etching rate to be ensured can be realized.

[0115] Although the present invention has been fully described inconnection with the preferred embodiments thereof with reference to theaccompanying drawings, it is to be noted that various changes andmodifications are apparent to those skilled in the art. Such changes andmodifications are to be understood as included within the scope of thepresent invention as defined by the appended claims unless they departtherefrom.

What is claimed is:
 1. A plasma processing method comprising: exhausting interior of a vacuum chamber while supplying gas into the vacuum chamber; and while controlling the interior of the vacuum chamber to a pressure, applying a high-frequency power of 100 kHz to 100 MHz to a coil provided in a vicinity of a dielectric window provided so as to face a substrate placed on a substrate electrode in the vacuum chamber, and thus generating plasma in the vacuum chamber to process the substrate or a film on the substrate by the generated plasma while particles which tend to move straight from a surface of the substrate or from a surface of the film on the substrate toward a wall surface of the dielectric window inside the vacuum chamber are kept interrupted by a metal plate.
 2. A plasma processing method according to claim 1, wherein when the plasma is generated inside the vacuum chamber, the high-frequency power of 100 kHz to 100 MHz is applied to the coil provided inside a dielectric cylinder serving as the dielectric window and outside a vacuum chamber.
 3. A plasma processing method according to claim 1 or 2, wherein the plasma processing is a process of etching the substrate or the film on the substrate.
 4. A plasma processing method according to claim 1 or 2, wherein the plasma processing is a process of etching a refractory metal film on the substrate.
 5. A plasma processing method according to claim 1 or 2, wherein the plasma processing is a process of etching a thin film formed on a refractory metal film on the substrate.
 6. A plasma processing method according to claim 4 or 5, wherein the refractory metal film is a film containing at least one element of iridium, rhodium, ruthenium, platinum, gold, copper, rhenium, bismuth, strontium, barium, zirconium, lead, and niobium.
 7. A plasma processing method according to claim 2, wherein the high-frequency power of 100 kHz to 100 MHz is applied to the coil provided outside the vacuum chamber on a dielectric cylinder serving as the dielectric window in a state that a first metal plate provided at a bottom portion of the dielectric cylinder inside the vacuum chamber is connected to a second metal plate provided at an upper portion of the dielectric cylinder on its one side opposite to the bottom portion inside the vacuum chamber by means of a metal rod or bolt extending through a penetration hole provided along an axis of the dielectric cylinder while the dielectric cylinder is fixed by being sandwiched between the first metal plate and the second metal plate.
 8. A plasma processing method according to claim 2, wherein the high-frequency power of 100 kHz to 100 MHz is applied to the coil provided outside the vacuum chamber on a dielectric cylinder serving as the dielectric window in a state that a first metal plate provided at a bottom portion of the dielectric cylinder inside the vacuum chamber is connected to a second metal plate provided at an upper portion of the dielectric cylinder on its one side opposite to the bottom portion inside the vacuum chamber by means of a metal rod or bolt disposed outside the vacuum chamber on the dielectric cylinder while the dielectric cylinder is fixed by being sandwiched between the first metal plate and the second metal plate.
 9. A plasma processing method according to claim 7 or 8, wherein the metal rod or bolt, the first metal plate, and the second metal plate are at a ground potential.
 10. A plasma processing method according to claim 7 or 8, wherein the processing is carried out in a state that a line segment interconnecting an arbitrary point on a vacuum-side wall surface of the dielectric cylinder and an arbitrary point on a surface of the substrate is interrupted by the first metal plate provided at the bottom of the dielectric cylinder.
 11. A plasma processing method according to claim 7 or 8, wherein a diameter of the first metal plate is 1 to 1.5 times larger than a diameter of the substrate electrode and a diameter of the second metal plate is 1.6 to 3 times larger than a diameter of the substrate electrode.
 12. A plasma processing method according to claim 7 or 8, wherein a distance between the first metal plate and the substrate electrode is 40 mm to 150 mm.
 13. A plasma processing method according to claim 1 or 2, wherein the vacuum chamber has a pressure not more than 10 Pa.
 14. A plasma processing method according to claim 1 or 2, wherein the vacuum chamber has a pressure not more than 3 Pa.
 15. A plasma processing apparatus comprising: a vacuum chamber; a gas supply equipment for supplying gas into the vacuum chamber; an exhaust equipment for exhausting the vacuum chamber; a pressure-controlling valve for controlling the vacuum chamber to an internal pressure; a substrate electrode for placing thereon a substrate in the vacuum chamber; a dielectric window provided so as to face the substrate electrode; a coil provided in a vicinity of the dielectric window; and a high-frequency power supply equipment capable of supplying a high-frequency power of 100 kHz to 100 MHz to the coil, wherein a line segment interconnecting an arbitrary point on a vacuum-side wall surface of the dielectric window and an arbitrary point on a surface of the substrate is interrupted by a metal plate.
 16. A plasma processing apparatus comprising: a vacuum chamber; a gas supply equipment for supplying gas into the vacuum chamber; an exhaust equipment for exhausting the vacuum chamber; a pressure-controlling valve for controlling the vacuum chamber to an internal pressure; a substrate electrode for placing thereon a substrate in the vacuum chamber; a dielectric cylinder provided so as to face the substrate electrode; a coil provided inside the dielectric cylinder and outside the vacuum chamber; and a high-frequency power supply equipment capable of supplying a high-frequency power of 100 kHz to 100 MHz to the coil.
 17. A plasma processing apparatus according to claim 16, further comprising: a first metal plate provided at a one-side bottom of the dielectric cylinder facing the substrate electrode; and a second metal plate provided at the other side bottom of the dielectric cylinder not facing the substrate electrode, wherein the first metal plate is connected to the second metal plate by means of a metal rod or a bolt extending through a penetration hole provided along a cylinder axis of the dielectric cylinder while the dielectric cylinder is fixed by being sandwiched between the first metal plate and the second metal plate.
 18. A plasma processing apparatus according to claim 16, further comprising: a first metal plate provided at a one-side bottom of the dielectric cylinder facing the substrate electrode; and a second metal plate provided at the other side bottom of the dielectric cylinder not facing the substrate electrode, wherein the first metal plate is connected to the second metal plate by means of a metal rod or a bolt provided through a space inside the dielectric cylinder while the dielectric cylinder is fixed by being sandwiched between the first metal plate and the second metal plate.
 19. A plasma processing apparatus according to claim 17 or 18, wherein the metal rod or bolt, the first metal plate, and the second metal plate are at a ground potential.
 20. A plasma processing apparatus according to claim 17 or 18, wherein a line segment interconnecting an arbitrary point on a vacuum-side wall surface of the dielectric cylinder and an arbitrary point on a surface of the substrate is interrupted by the first metal plate provided at the bottom of the dielectric cylinder.
 21. A plasma processing apparatus according to claim 17 or 18, wherein a diameter of the first metal plate is 1 to 1.5 times larger than a diameter of the substrate electrode and a diameter of the second metal plate is 1.6 to 3 times larger than a diameter of the substrate electrode.
 22. A plasma processing apparatus according to, claim 17 or 18, wherein a distance between the first metal plate and the substrate electrode is 40 mm to 150 mm.
 23. An etching method comprising: controlling interior of a vacuum chamber to a pressure by exhausting the vacuum chamber while supplying gas into the vacuum chamber; and applying a high-frequency power of 100 kHz to 100 MHz to a coil provided inside a dielectric cylinder and outside the vacuum chamber provided so as to face a substrate placed on a substrate electrode in the vacuum chamber, thus generating plasma in the vacuum chamber so as to etch a refractory metal film on the substrate.
 24. An etching method comprising: controlling interior of a vacuum chamber to a pressure by exhausting the vacuum chamber while supplying gas into the vacuum chamber; and applying a high-frequency power of 100 kHz to 100 MHz to a coil provided inside a dielectric cylinder and outside the vacuum chamber provided so as to face a substrate placed on a substrate electrode in the vacuum chamber thus, generating plasma in the vacuum chamber so as to etch a thin film formed on a refractory metal film on the substrate.
 25. An etching method according to claim 23 or 24, wherein the refractory metal film is a film containing at least one element of iridium, rhodium, ruthenium, platinum, gold, copper, rhenium, bismuth, strontium, barium, zirconium, lead, and niobium.
 26. An etching method according to claim 23 or 24, wherein the etching is carried out in a state that a first metal plate provided at a one-side bottom of the dielectric cylinder facing the substrate electrode is connected to a second metal plate provided at the other side bottom of the dielectric cylinder not facing the substrate electrode, by means of a metal rod or a bolt extending through a penetration hole provided along a cylinder axis of the dielectric cylinder while the dielectric cylinder is fixed by being sandwiched between the first metal plate and the second metal plate.
 27. An etching method according to claim 23 or 24, wherein the etching is carried out in a state that a first metal plate provided at a one-side bottom of the dielectric cylinder facing the substrate electrode is connected to a second metal plate provided at the other side bottom of the dielectric cylinder not facing the substrate electrode, by means of a metal rod or a bolt provided in a space inside the dielectric cylinder while the dielectric cylinder is fixed by being sandwiched between the first metal plate and the second metal plate.
 28. An etching method according to claim 26 or 27, wherein the metal rod or bolt, the first metal plate, and the second metal plate are at a ground potential. 